What is this article about?

Sex addiction was first formulated in the 1980’s and is often compared with drug addiction. While the notion is widely accepted, not everyone is fully convinced by it.

This study presents a model of sexual addiction, which involves a combination of models based upon the dual-control organisation of behavior and brain, and the incentive motivation theory. Two criteria suggest addiction:

• There is suffering and a desire to be free of the excessive behavior.
• There is a specific set of causal processes and learning mechanism involved.

Sex addiction includes both addiction to pornography and sexual behavio

What characterizes the process underlying motivation?

Two dichotomies are important. First, the control of behavior has a dual structure: goal based (goal-driven) and stimulus based (compulsive). Second, there are corresponding inhibition processes that are also based on a dual structure.

When it comes to addiction, stimulus based control of behavior has two components:

1. Kahneman’s concept of dual control is explained by an automatic and fast System 1 that can act unconsciously (stimulus based), and a goal-directed, slow and intentional System 2 that has conscious control (goal based). The distinction between these systems refers to the control thought and behavior, and therefore also applies to addiction. When experiences are repeated, behavior becomes more like a habit, for example the actions involved in getting access to and using drugs.
2. The targets of behavior gain increased power to lure the addict, like a magnet. This aspect is characteristic of motivational processes, especially in addiction.

What is incentive motivation?

According to the incentive-motivation theory of Robinson and Berridge (1993), motivational triggers are:

•  Certain incentives in the external world, like drugs and possible sexual partners.
•  Cues linked to these incentives, for example the link between a PC keyboard and pornography.
•  Internal representations of the incentives in memory.

The incentive motivation model forms the basis of this article, as it is relevant to behavioral addictions, including sex.

The activation of a number of brain regions as a reaction to cues (seeing drugs or pornographic images) is known as cue reactivity. Addicts have a tendency to show an approach bias towards the target of the addiction. In case of sex and drugs, the stimulus-based control can act unconsciously until the on-going approach response reaches awareness. There is a difference between ‘wanting’ and ‘conscious wanting’. The magnitude of the approach bias towards sexual cues is higher in people with a problematic use of pornography.

There is a difference between liking and wanting. Drugs can become intensely wanted even though it was not liked after taken it. Despite being different processes, there is a strong interaction between liking and wanting. People usually want what they like and like what they want. However, studies show that a high value of sexual wanting does not necessarily mean a high liking. Sex addicts even mentioned experiencing less or no pleasure over time.

Rewards like sex and food activate a brain network which involves the ventral striatum, anterior insula, ventromedial prefrontal cortex and amygdala. The pathway of dopaminergic neurons from the ventral tegmental area to the nucleus accumbens plays a key role in analyses of incentive motivation. Activity in that pathway merely underlies wanting. Liking is mostly a matter of opioids. Repeated activation of the pathway results into ‘incentive sensitization’, which refers to the capacity of sexual stimuli or drugs to trigger the pathway becomes sensitized. Studies have demonstrated that males with a problematic use of pornography show a higher reactivity to erotic cues in several brain regions. They expressed a strong wanting but not a stronger liking compared to a control group.

When it comes to the goal-based control of behavior and addiction, the goal is based upon the hedonic representation of the reward in the brain, which involves the ventromedial prefrontal cortex. This influences the wanting and inhibits the tendencies that are not compatible with the goal.

What is the relevance of inhibition to sex addiction?

There are processes of active inhibition on sexual behavior and desire. The loss of sexual desire is caused by a loss of excitation and by the opposite of excitation: inhibition. Both inhibition and excitation are represented by dual controls. A possible clash is the resistance of temptation (incentive versus goal).

There are two types of inhibition regarding sexual behavior: due to fear of 1) performance consequences and 2) performance failure. In the context of the dual control concept, the fear of performance consequences corresponds with goal-driven inhibition (wanting to stay loyal) and the fear of performance corresponds with stimulus-driven inhibition (smell, sounds, erectile functioning). The neurotransmitters serotonin and dopamine are responsible for respectively inhibition and excitation.

There is a strong interaction between the two control modes. How the controls are ‘weighted’ depends on the circumstances. When a temptation is resisted, it is assumed that System 2 inhibits the tendency to give in. Sometimes, cognition distortion happens, in which the conscious system tells itself it’s alright to give in.

Behavior becomes more impulsive and stimulus-based when the arousal is high and restraints from the conscious system are outweighed. This is also known as heat-of-the-moment. Repeated experience can lead to an automatic control of behavior, which relates to sexual addiction. Sexual behavior can get ‘out of control’ and after a while actions ‘just happen’.

Fantasy plays an important role in sex addiction. The brain regions that are excited by seeing drugs show the same response by thinking of it. Fantasy might also excite incentive motivation processes that underlie sexual desire.

It is assumed that a sex addiction offers a regulatory function, such as regulating the mood. The mood of non-addicts is maintained by social interactions. Many addicts struggle with attachment, their behavior tries to make up for the lack of social interactions. In the context of biology, regulating behavior is influenced by low opioid levels. The control actions are rooted in dopamine.

The majority of sex addicts is male (80% in 1998). Males are more likely to engage in pornography, paraphilias and paid sex. Women are more likely to associate sex with love.

Several evolutionary arguments explain these statistics:

• Supernormal stimuli. Pornography and sex are more easily available in the current sexual environment.
• Sex differences. Men have a stronger response to erotic stimuli, which implies a corresponding appetitive incentive value of erotic stimuli. Men are more likely to have a mere sex addiction, whereas women tend to be addicted to love. The sexual desire of females is influenced by feeling valued, while the desire of men is driven by appearance and novelty.

The concept of sex addiction has been criticized by several authors. They argue that the elements of risk, escalation, difficulties in regulation, tolerance and withdrawal symptoms are not present in sexual behaviors. However, it has been proven that sexually-addicted people have difficulties in regulation their urges. Tolerance: needing to do more of something to achieve the same effect. Like an increased dose of drugs over time, sexual activity can also be increased. The same goes for the level of risk. Some sex addicts have reported withdrawal symptoms (anxiety, depression, sleep disorders, tension).

The presence of comorbidity offers valuable insights into sexual addiction. Other conditions either have certain features in common or are addictive in combination with sex. Examples are drugs and alcohol abuse, ADHD, bipolar disorder, borderline personality disorder, Parkinson’s disease, stress and depression.

How does a sex addiction develop?

Whether an activity becomes addictive depends upon the phase in which it was first performed. Adolescence and early adulthood are vulnerable periods, in which many sex and drugs addictions start. It is assumed that addiction is often the result of failing to find secure attachment as an infant (attachment theory), as it triggers the need for compensation. Brain development also plays a role: the development of the relevant subcortical regions during adolescence increases the chances of activities becoming addictive. These changes can also be increased due to childhood abuse. People who suffer from early life adversity (sexual, psychological or physical abuse) are more likely to engage in risky sexual behavior.

What are alternative explanatory models?

Out-of-control sexual behavior can be explained by the following alternative models: obsessive-compulsive disorder, a high drive, hypersexuality and impulsive disorder. Sometimes, these are more suitable terms for the phenomena than ‘addiction’, but they can also co-exist with addiction. Impulsivity, compulsivity and hypersexuality can co-exist with problematic sexual behavior.

How is sexual addiction treated?

Sex addicts have an excess weight of excitation compared to inhibition. Therapists try to increase the relative weight of inhibition, by shifting the weight to goal-based control. Certain biological interventions have proved to be successful, for example prescribing selective serotonin reuptake inhibitors, opioid antagonist naltrexone or testosterone blockers. Another method is the excitatory electrical stimulation of the prefrontal cortex. Psychotherapeutic interventions are acceptance and commitment therapy (ACT), goal-setting and mentalization-based therapy. An example of behavioral interventions is looking at pictures of loved ones at moments of temptation.